Complete the recursive formula of the arithmetic sequence $4, 22, 40, 58,...$. $b(1)=$
Explanation: The first term is $4$ and the common difference is $18$. ${+18\,\curvearrowright}$ ${+18\,\curvearrowright}$ ${+18\,\curvearrowright}$ $4,$ $22,$ $40,$ $58,...$ This is the recursive formula of $4, 22, 40, 58,...$ $\begin{cases} b(1)=4 \\\\ b(n)=b(n-1)+18 \end{cases}$